Doppler Radar Echo Characteristics of a Hail Process

In this paper, the conventional meteorological data and Doppler weather radar data were used to analyze the severe convective storm after a systematic precipitation occurred in July 28, 2007 in Yili, Xinjiang. The results showed that this convective storm occurred abruptly, instantaneously and severely although there was no an advantageous circulation background. The primary favorite factors for the local convective storm were the high surface temperature, the high surface humidity and the incompletely liberated upper energy. This hail process appeared in a severe storm, whose reflectivity in mature stage was larger than 50 dBz, and there were an adverse wind area, the convergent cyclonic velocity pair, as well as lower level convergence and upper level divergence. It was also discovered that the effective parameters for forecasting hail intensity are: the strong echo area extending to above the -20 ℃ isothermal, the strong divergence with big difference between the positive and negative velocities, the persistence of 50 kg·m-2 VIL, as well as the sudden increase of VIL.